3,776 research outputs found
Hypermobility, developmental coordination disorder and physical activity in an Irish paediatric population
OBJECTIVE: The primary aim of the study was to explore the prevalence of generalized joint hypermobility (GJH) and generalized hypermobility spectrum disorder (gHSD) using the new classification system in a community paediatric physiotherapy service in Ireland. The second aim was to explore the relationship between GJH, gHSD and physical activity level, while considering the association of probable developmental coordination disorder (pDCD). METHODS: A case-controlled cross-sectional study of children aged 6-12 years, recruited from the community paediatric physiotherapy department (n = 32) and a local school (n = 41), was carried out. A Beighton score of â„6/9 distinguished GJH. The new framework for hypermobility spectrum disorder (HSD) was used. Self-reported physical activity level was measured using the Physical Activity Questionnaire-Older Children. A parent-reported validated questionnaire screened for pDCD. RESULTS: The prevalence of GJH was 21.9% of children attending physiotherapy. One child in the physiotherapy group was identified as having gHSD, with a prevalence of 3.1%. There was no significant difference in physical activity level between children with and without GJH attending physiotherapy (independent samples t-test, p = 0.28). Probable developmental coordination disorder (pDCD) was observed in 71.9% of children attending physiotherapy. There was no significant difference in the number of children with pDCD in those with and without GJH (Fisher's exact test, p = 0.370). CONCLUSIONS: This study was the first to explore the prevalence of GJH and gHSD in the paediatric physiotherapy population in Ireland. The presence of GJH did not affect self-reported physical activity level or motor coordination in children attending physiotherapy
On the ergoregion instability in rotating gravastars
The ergoregion instability is known to affect very compact objects that
rotate very rapidly and do not possess a horizon. We present here a detailed
analysis on the relevance of the ergoregion instability for the viability of
gravastars. Expanding on some recent results, we show that not all rotating
gravastars are unstable. Rather, stable models can be constructed also with
J/M^2 ~ 1, where J and M are the angular momentum and mass of the gravastar,
respectively. The genesis of gravastars is still highly speculative and
fundamentally unclear if not dubious. Yet, their existence cannot be ruled out
by invoking the ergoregion instability. For the same reason, not all
ultra-compact astrophysical objects rotating with J/M^2 <~ 1 are to be
considered necessarily black holes.Comment: 10 pages, 7 figure
Parametric coupling between macroscopic quantum resonators
Time-dependent linear coupling between macroscopic quantum resonator modes
generates both a parametric amplification also known as a {}"squeezing
operation" and a beam splitter operation, analogous to quantum optical systems.
These operations, when applied properly, can robustly generate entanglement and
squeezing for the quantum resonator modes. Here, we present such coupling
schemes between a nanomechanical resonator and a superconducting electrical
resonator using applied microwave voltages as well as between two
superconducting lumped-element electrical resonators using a r.f.
SQUID-mediated tunable coupler. By calculating the logarithmic negativity of
the partially transposed density matrix, we quantitatively study the
entanglement generated at finite temperatures. We also show that
characterization of the nanomechanical resonator state after the quantum
operations can be achieved by detecting the electrical resonator only. Thus,
one of the electrical resonator modes can act as a probe to measure the
entanglement of the coupled systems and the degree of squeezing for the other
resonator mode.Comment: 15 pages, 4 figures, submitte
Two Tongues, One Brain: Imaging Bilingual Speech Production
This review considers speaking in a second language from the perspective of motorâsensory control. Previous studies relating brain function to the prior acquisition of two or more languages (neurobilingualism) have investigated the differential demands made on linguistic representations and processes, and the role of domain-general cognitive control systems when speakers switch between languages. In contrast to the detailed discussions on these higher functions, typically articulation is considered only as an underspecified stage of simple motor output. The present review considers speaking in a second language in terms of the accompanying foreign accent, which places demands on the integration of motor and sensory discharges not encountered when articulating in the most fluent language. We consider why there has been so little emphasis on this aspect of bilingualism to date, before turning to the motor and sensory complexities involved in learning to speak a second language as an adult. This must involve retuning the neural circuits involved in the motor control of articulation, to enable rapid unfamiliar sequences of movements to be performed with the goal of approximating, as closely as possible, the speech of a native speaker. Accompanying changes in motor networks is experience-dependent plasticity in auditory and somatosensory cortices to integrate auditory memories of the target sounds, copies of feedforward commands from premotor and primary motor cortex and post-articulatory auditory and somatosensory feedback. Finally, we consider the implications of taking a motorâsensory perspective on speaking a second language, both pedagogical regarding non-native learners and clinical regarding speakers with neurological conditions such as dysarthria
A five year record of high-frequency in situ measurements of non-methane hydrocarbons at Mace Head, Ireland
Continuous high-frequency in situ measurements of a range of non-methane hydrocarbons have been made at Mace Head since January 2005. Mace Head is a background Northern Hemispheric site situated on the eastern edge of the Atlantic. Five year measurements (2005â2009) of six C<sub>2</sub>âC<sub>5</sub> non-methane hydrocarbons have been separated into baseline Northern Hemispheric and European polluted air masses, among other sectors. Seasonal cycles in baseline Northern Hemispheric air masses and European polluted air masses arriving at Mace Head have been studied. Baseline air masses show a broad summer minima between June and September for shorter lived species, longer lived species show summer minima in July/August. All species displayed a winter maxima in February. European air masses showed baseline elevated mole fractions for all non-methane hydrocarbons. Largest elevations (of up to 360 ppt for ethane maxima) from baseline data were observed in winter maxima, with smaller elevations observed during the summer. Analysis of temporal trends using the Mann-Kendall test showed small (<6 % yr<sup>&minus;1</sup>) but statistically significant decreases in the butanes and <i>i</i>-pentane between 2005 and 2009 in European air. No significant trends were found for any species in baseline air
Rosmarinic acid in Canna generalis activates the medial deterrent chemosensory neurone and deters feeding in the tobacco hornworm Manduca sexta
For all but a very few highly specialized insect feeders, Canna generalis L. (Cannaceae) is unacceptable as a food plant and is a highly potent feeding deterrent for the tobacco hornworm Manduca sexta Johan. (Lepidoptera). The present study describes the isolation of an active deterrent compound, rosmarinic acid (RA) from the ethanol extract of canna leaves. A twoâchoice bioassay shows that RA is a feeding deterrent in the concentration range 0.3â3 mm. Bilateral ablation of the oral chemoreceptors eliminates this deterrence. The results reported in the behavioural literature show that only the epipharyngeal sensilla and the medial (but not the lateral) styloconica contribute to this deterrence elicited by canna foliage or extract, and the data obtained in the present study show the same results using RA. Electrophysiological recordings from the medial styloconica show that RA primarily stimulates the âdeterrent neuroneâ in a concentrationâdependent manner with a threshold of approximately 0.03 mm and a peak frequency of 69 spikes sâ1 at 0.1 mm RA. An extract of canna leaves elicits similar responses. Adding RA to canna extract does not elicit another class of spikes, indicating that both stimuli activate the same neurone. We discuss the significance of the results with respect to furthering our knowledge about the sensory basis of food selection, and specifically about the range of compounds that stimulate deterrent chemosensitive neurones of lepidopteran larvae
Dynamics of thermoelastic thin plates: A comparison of four theories
Four distinct theories describing the flexural motion of thermoelastic thin
plates are compared. The theories are due to Chadwick, Lagnese and Lions,
Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the
temperature but is considered the most accurate as the others are derivable
from it by different approximations. Attention is given to the damping of
flexural waves. Analytical and quantitative comparisons indicate that the
Lagnese and Lions model with a 2D temperature equation captures the essential
features of the thermoelastic damping, but contains systematic inaccuracies.
These are attributable to the approximation for the first moment of the
temperature used in deriving the Lagnese and Lions equation. Simmonds' model
with an explicit formula for temperature in terms of plate deflection is the
simplest of all but is accurate only at low frequency, where the damping is
linearly proportional to the frequency. It is shown that the Norris model,
which is almost as simple as Simmond's, is as accurate as the more precise but
involved theory of Chadwick.Comment: 2 figures, 1 tabl
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